On the difference in the mode of ossification of the first and other metacarpal and metatarsal bones / by Allen Thomson.

  • Thomson, Allen, 1809-1884.
Date:
[1868?]
Catalogue details

Licence: Public Domain Mark

Credit: On the difference in the mode of ossification of the first and other metacarpal and metatarsal bones / by Allen Thomson. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    occurring in the centre of the cartilaginous matrix of the shaft at an early period, which varies in the different bones, ac- cording to their position in the series, from the 8th or 9th to the 12th or 13th weeks. From this primary centre the ossifi- cation extends in the cartilage with the usual changes attendant on the formation of medullary spaces, and finally of a medul- laiy canal, if such exists; and the greater part of the bone forming the shaft Is completed by this process, and by the know’n superposition of the subperiosteal layers. At the period of birth in all of them a considerable mass of cartilage still remains at each extremity of the bone. In these cartilaginous masses the ossific nuclei of the epiphyses appear in those extremities in wjiich bony epiphyses are to l>e formed; but the commence- ment of their deposition date.s considerably later than the pri- mary ossification, at a variable period between the third and fifth or sixth years; or even one or two years later. In those ends of the bones where no epiphyses are to be formed, the origiiuxl cartilaginous ossification of the shaft gra- dually extends itself into the tenninal cartilage; but when a se]>arate epiphysis occurs, although the main ossification also extends somewhat towards that extremity, it is met by that of the epiphysal nucleus, the two parts of bone being for a time divided by the remains of cartilage. There is therefore a marked distinction between the ossification of an epiphysLs, which is almost entirely cartilaginous, and that proceeding from the original nucleus of the shaft, which internally is car- tilaginous, but superficially is subperiosteal The general fact is well known in regard to the larger l)onea that the separate epiphyses which soonest become united by l)one to the shaft are the latest in the commencement of their ossification; and we see this general fact well illustrated in the l>ono8 of the hand and foot, in connection either with the early consolidation or the entire absence of an epiphysis at one extremity. In now proceeding to mention shortly the result of the observations I have made, I will refer to the figures of p. 144 to explain more fully the appearances described. In all cases which I have examined at a sufficiently early age, that is, about